code: def build_hidden_layer(self):
      raise NotImplementedError
  
file_path: dgl/examples/mxnet/rgcn/model.py
imports: import mxnet
  from mxnet import gluon
label_desc: Use image node_id 4 for calling the BaseRGCN obj's underlying member method code with example usage: obj.build_hidden_layer() without return types